Expansion of connective tissue, especially skin, fascia, cartilage and tendon, is often desirable for cosmetic or functional purposes. Achieving tissue expansion without damaging, impairing, or aesthetically harming the tissue is a common concern in reconstruction after surgery, trauma, and for various medical and congenital disorders. Tissue expansion can be used for tension relief of contracted surgical, traumatic, and burn scars. For example, burn victims often suffer through many painful surgeries performed to relieve the tension and contraction of hypertrophic scars. After excision of skin cancer on the forehead and scalp, large defects are often left to heal openly because the surrounding skin cannot be moved enough to close the wound. On the legs, skin healing can be poor and the skin is relatively inelastic, such that surgical wounds and ulcers on the legs are difficult to close. Scalp reduction surgery can be limited by the rigidity of scalp skin. In addition to a need for tissue stretching of skin in these examples, tissue stretching can also be useful for lengthening tendons, re-shaping cartilage, and for expanding other connective tissues.
Conventional techniques for stretching tissue include, e.g., (a) subcutaneous implantation of saline-filled balloons to expand the skin prior to surgery, (b) using incisions to create various artful flaps that move skin from one location to another without removing it entirely, such that tension is relieved and/or missing tissue is replaced by mobilizing the surrounding tissue, and (c) tissue grafts, which involve removal of skin or other connective tissue from one location and placing it on another location. Tissue grafts can be used to replace skin or other tissue that has been removed by surgery or trauma. For example, split-thickness skin grafts can be used to cover a wound in burn and skin ulcer patients. A conventional split-thickness graft can be made, e.g., by harvesting a sheet of epidermis and upper dermis tissue from a donor site, much like peeling an apple, which can then be placed on the burn or ulcer location. The skin tissue can then grow back on the donor site following a generally extended healing time.
Split thickness grafts may often be “meshed” for expansion, so they can cover a larger area than the donor site. Conventional tissue meshing includes formation of an array of many slits, typically several millimeters in length or longer, which can open into diamond-shaped or lens-shaped holes when the meshed graft is subjected to tension and expanded. These holes can facilitate an overall expansion of the graft. The expanded meshed tissue sheet generally may have an appearance of a chain-link fence, with large holes that can remain visible after the graft is placed and the tissue is healed. Thus, meshed grafts may save a burn victim's life by expanding the usable area of skin available from donor sites, but they also can contribute to life-long aesthetic disfigurement.
Conventional full-thickness grafts generally include a removal of epidermal tissue and the complete thickness of the dermis from a donor site to be used as a graft, with the edges of skin adjacent to the removed tissue being re-opposed at the donor site. Meshing may not be ideal for expanding full-thickness grafts because, for example, (a) the lens-shaped holes left by gross meshing and expansion of full-thickness skin can be even more disfiguring than in split-thickness grafts because they are much deeper, and may look like an array of acne scars after healing, and (b) the large, full-thickness holes can take weeks to heal because cells from the surrounding dermis have to build new fibrotic tissue to fill in the substantial volume of each hole. Similarly, meshing of flaps may not be appropriate because skin incisions within a flap can sever some of the blood supply to the flap, thus impairing the viability of the flap tissue. For these reasons, conventional tissue meshing may generally not be suitable for expansion of skin grafts or flaps during surgery, and not for relief of tension on scars, nor to modify the scar tissue itself.
Accordingly, there can be a need to address and/or overcome at least some of the deficiencies or issues described herein above.